"Different Worlds for Very Different Folks..."
Planet 1
From Cycle of Fire, by Hal Clement
The planet Abyormen is in a double-star system in the Pleiades. It occupies a very elliptical orbit around the red dwarf star Theer, which itself orbits the larger blue giant sun Alcyone. The planet thus has a "short year" around the dwarf, with the usual seasonal changes, and a "long year" of about 65 Earth Years in length.
For half the "long year" (or about 32 earth years) at a time, the planet is more or less Earth-like in climate, although it can get fairly cold at the most distant part of its orbit. However, as the planet approaches the giant star in its orbit the temperatures rise well above the boiling point of water for 20 earth years.
"Different Worlds for Very Different Folks..."
Planet 2
From Close to Critical, by Hal Clement
The planet has an average daily temperature of 212°F (100°C) - the boiling point of water. During the day, the temperature is 220°F-240°F and all water is gas (steam). At night the temperature drops to 190°-200°F and all water condenses into liquid.
"Different Worlds for Very Different Folks..."
Planet 3
From Mission of Gravity and Starlight, by Hal Clement
The planet Mesklin is very large, and thus has a very high gravity - 700 or more times that of Earth. However, the planet spins very rapidly about its axis, so that a day is only 90 minutes long. This means that the gravity is that great only at the poles - centrifugal force lessens the gravity as one approaches the equator, so that the gravity at the equator is only about three times Earth's. Its oceans are methane, and it snows solid ammonia.
Points to think about:
How might the Mesklinites view their strange world?
What effect might these conditions have on Mesklin's weather patterns?
What about the Coriolis effect on such a rapidly spinning body?
"Different Worlds for Very Different Folks..."
Planet 4
From the "known space" universe by Larry Niven, including the novel Ringworld and various short stories.
The "Outsiders" live in the vacuum of outer space. They travel from star to star following the "starseeds" and trade information with the cultures they meet along the way.
Questions: How can the "Outsiders" live?
What kind of structures might they build?
"Different Worlds for Very Different Folks..."
Planet 5
From The Ship Who Sang, by Anne McCaffrey
The planet Beta Corvi is a gas giant planet much like Jupiter. There is no solid surface at all, but just a very deep atmosphere of methane and ammonia and other gasses. The atmosphere gets increasingly dense and hot as you approach the center of the planet. Although the various gasses in the atmosphere will tend to separate into layers, tremendous storms (like Jupiter's Red Spot) can occur and mix the gaseous layers together. The gravity at the center of the planet is very high - many times Earth's - but at the edges of the atmosphere there is very little gravity.
"Different Worlds for Very Different Folks..."
Planet 6
From "Flare Time," a short story by Larry Niven
The planet Medea is in a triple star system: the red giant star Argo, and two red dwarfs. The planet's rotation matches its year around Argo, so that it keeps one hemisphere (the "Hot End" - temperature above the boiling point of water) toward Argo, and the other hemisphere (the "Cold End" - cold enough to freeze carbon dioxide) always in darkness. Air and water are heated in the hot end, flow constantly to the cold end as high-altitude winds, and then cool and flow back at the surface. Humans can live in the twilight zone between ends, where it is always about as dark as a moonlit night on earth. The planet's libration (wobbling in orbit) allows Argo to rise a little above the horizon and set about once an earth week, and the two dwarfs rise and set conventionally. However, at unpredictable times the dwarf stars have enormous flares. During a flare, the star becomes many times brighter than Earth's sun for a period of less than a day.